Blank disks appear as unidentified Media until a On Media Label (OML) is written on the media. If auto-stamping options are enabled, the system writes an OML as soon as the media is detected. If auto-stamping options are not enabled the system writes an OML when a data protection job is initiated. You can also stamp the media manually and create an OML so that media is identified.
See Media Labeling in Stand-Alone Drives for more information.